Serialize annotations on type parameters in builtins

compiler/serialization/src/org/jetbrains/kotlin/serialization/SerializerExtensionBase.kt

@@ -71,4 +71,10 @@ open class KotlinSerializerExtensionBase(private val protocol: SerializerExtensi
             proto.addExtension(protocol.typeAnnotation, annotationSerializer.serializeAnnotation(annotation))
         }
     }
+
+    override fun serializeTypeParameter(typeParameter: TypeParameterDescriptor, proto: ProtoBuf.TypeParameter.Builder) {
+        for (annotation in typeParameter.annotations) {
+            proto.addExtension(protocol.typeParameterAnnotation, annotationSerializer.serializeAnnotation(annotation))
+        }
+    }
 }

compiler/testData/serialization/builtinsSerializer/typeParameterAnnotation.kt

@@ -0,0 +1,6 @@
+package test
+
+@Retention(AnnotationRetention.BINARY)
+@Target(AnnotationTarget.TYPE_PARAMETER)
+annotation class Ann(val value: String)
+inline fun <reified @Ann("abc") T> foo() {}

compiler/testData/serialization/builtinsSerializer/typeParameterAnnotation.txt

@@ -0,0 +1,8 @@
+package test
+
+public inline fun </*0*/ reified @test.Ann(value = "abc") T> foo(): kotlin.Unit
+
+@kotlin.annotation.Retention(value = AnnotationRetention.BINARY) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.TYPE_PARAMETER}) public final annotation class Ann : kotlin.Annotation {
+    public constructor Ann(/*0*/ value: kotlin.String)
+    public final val value: kotlin.String
+}

compiler/tests/org/jetbrains/kotlin/serialization/builtins/BuiltInsSerializerTest.kt

@@ -62,6 +62,10 @@ class BuiltInsSerializerTest : TestCaseWithTmpdir() {
         doTest("simple.kt")
     }
 
+    fun testTypeParameterAnnotation() {
+        doTest("typeParameterAnnotation.kt")
+    }
+
     fun testNestedClassesAndObjects() {
         doTest("nestedClassesAndObjects.kt")
     }